BRIAN WILLIAMS: NBC News poll we released just last night, 55 to 35, you against Senator John McCain. American respondents are telling us they view you as the riskier choice for President. Do you understand that? To what do you attribute that?

SENATOR OBAMA: "It's not surprising that people would say that the guy we're more familiar with is the less riskier choice. That doesn't answer the broader question, though, which is what do Americans think we need right now?" Obama said. "And can we afford to have four more years or eight more years of the same types of policies that we've had for the past eight?

"And in some ways, I guess that would be safe. It's the devil you know versus the devil you don't. But-- but I think the American people understand that we're in a time of profound challenge and that we've got to make some significant changes-- in how our economy works, in how our tax policy is structured, in our energy policy and our foreign policy if we're gonna meet those challenges."

Obama also discussed Iran, his trip abroad, and John McCain's assertion that Obama "would rather lose a war in order to win a political campaign."